15 Causes Why Your Window AC is Leaking Water Inside or Outside the House


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You spent an entire day under the sun and the moment you arrive at home, you can’t wait to switch on your air conditioning unit to save yourself from the heat.

But, have you ever experienced letting it run, only to be met by the sight of water seeping into the room that seems to be coming from your unit?

Air conditioning units should only produce cold air, so if you see water on the floor or dripping water outside the house that you think is coming from your AC unit, it is always a cause for concern.

On this page:

  • Although both a split and window AC unit have equal chances of leaking,  it happens more often inside the house rather than outside. It doesn’t really matter if you have one manufactured by Haier, Comfort-Aire, Frigidaire, or Kenmore, or any other brand, leaking is always a possibility.

    window ac

    But before you head on to Sears or your nearest appliance store and order a portable air conditioner instead, such as those made by Soleus, know that your leaking window unit may still be fixed.

    Even if it has yet to happen to you, it pays to be informed about the possible causes and what you should do about it. All these are what we will talk about throughout this article.

    And, as a bonus, we will let you know how you can easily find an HVAC contractor to fix the issue without you breaking a sweat.

    Sounds good?

    Then, continue reading.

    What Causes an Air Conditioner to Leak Water?

    A leaking air conditioner doesn’t just happen to old units; relatively new ones can also do so in just a short time after its installation. And, there is no all-encompassing reason why it happens; there are a myriad of possibilities for leaks.

    Leaks coming from a window unit are much easier to confirm because it is standalone, and any leak coming from it is easily visible.

    But if you have a split-level unit, or your air conditioning is part of a HVAC system spanning your entire home, the leak may be harder to trace. You also have to deal with the possibility that the leak is coming from another source, such as your air handler.

    And if you don’t know, water is produced by all AC units when warm air coming inside the unit interacts with the evaporator coil, whose function is to cool that air down. Condensation is then produced on the coils of the unit, which is supposed to go down the drain pan and lines. Leaks happen when this path is not followed.

    Tracing a leak is not as easy as it sounds. Sure, you may see the dripping water or puddles on the floor, but their presence will not immediately tell you what caused the leak. This is why it is challenging to pinpoint the exact cause of a leak in an AC unit.

    But before you or a professional can attempt to find out the cause of the leak, remember that safety is always a priority, especially since you have to deal with an electrical appliance affected by water.

    It is important to switch off your air conditioner before investigating the leak to prevent any injury, as well as damage to your unit. Your house can also sustain damage if it becomes saturated with water, that is why it is vital to mop up the water asap.

    Whichever type of AC unit you have, they have similar possible causes of air conditioner leaks. It may be because of one of the following possible causes, or a combination of them:

    • Too much condensation – while it is normal for air conditioners to have condensation present, what is not considered normal is when there is too much that you can already see water on the floor.
    • Issue with the drain pan – water may be dripping, instead of draining properly, because the drain pan is damaged or blocked. Some installers even fail to install them altogether.

    While this is common to older units, Sears window units, also branded as Kenmore, are often affected by this issue. However, this can also affect even those units manufactured by other brands, such as Frigidaire, LG, or GE.

    • Condensate pump is malfunctioning – leaking because of the condensate pump is likely due to clogging present in the pump.
    • Improperly sealed air conditioner – a window unit has to completely sealed on all sides when installed. If not, too much moisture can result.
    • Lower outdoor temperature compared to inside your home – sometimes, the issue is just as simple as temperature differences. Leaks can be produced when there is less evaporation happening, due to more moisture present on the air outside the room or rain itself. This happens when it is colder outside your home.

    Note that this issue affects window units more than split-type ones.

    • Loose drain line connections – over time, connections can loosen up or completely disconnect. When this happens, water will flow out of the gaps present.
    • Blockage on the condensate drain line – it is not just loose connections that can occur on your unit’s drain lines that can cause leaks. It can also happen due to clogging somewhere along the drain line.
    • Evaporator coils are damaged or dirty – if dirt or other debris are present on the coils of your unit, it will run less efficiently and cause the coils to freeze up and eventually leak.
    • Insufficient refrigerant present – any AC unit uses refrigerant in its operation. When it is at a low level, this will also cause freezing on the evaporator coils, resulting in leaks.
    • Improperly installed unit – while any appliance should be properly installed, window AC units, in particular, have serious consequences for wrong installation.

    Leaks can occur when the unit lacks the required pitch, allowing water to flow into the room, instead of going out the drain hole.

    • Dirty air filters – AC units have air filters that require regular cleaning. If you have a dirty air filter, its efficiency is affected and it can also trigger the formation of too much condensation.
    • Ducts are poorly insulated – the ducts and vents connected to your AC unit are also possible condensation spots, especially if they lack proper insulation. Continuously running a unit with insulation issues will also lead to leaks.

    Your unit’s coils also require insulation, and this aids in leading the condensation go down the drain lines.

    • Problems with the joint – a split unit is connected to the drain line via a joint, which can get damaged or succumb to wear and tear over time. Damage to this joint will also cause leaking on your unit.
    • Condensate trap is incorrectly installed or designed – condensate traps should help the moisture produced by your unit to flow properly along the drain lines, but sometimes, they can actually cause clogging if it is unsuitable for the unit.
    • Drain line does not come with p-traps or air vents – drain lines are prone to causing leaks when water starts backing up. To prevent this, p-traps or vents are added to it.

    With so many possible reasons, and the fact that it can involve internal components of an AC unit, it is no wonder why tracing the exact cause of a leak is a tough task that leaves typical homeowners stumped.

    Window AC Leaking Water Inside the House

    Now that you have an idea of the general causes of water leaks coming from an air conditioner, it’s time to go to the specifics.

    Leaking from your window unit is much easier to see, especially when there is water on the floor. And once it does, it can be due to any of these reasons:

    • Little to no pitch present because the unit was installed wrongly, allowing water to flow into the room, instead of outside
    • Frozen evaporator coils, because the air filter is dirty or the refrigerant is running low
    • Coils themselves are dirty
    • Issues with the drain lines, such as clogging and loose connections
    • Drip pan is clogged up with dirt or debris or damage
    • It is colder outside, or the air outside is too moist
    • Damaged condenser pump
    • Insufficient sealing around the unit

    In most cases, water leaking from your unit inside the house is due to installation issues or problems with the evaporator coils.

    Window AC Leaking Water Outside the House

    On the other hand, finding out if your unit is leaking outside the house can be challenging. You might see water dripping down from your AC unit, but you cannot immediately conclude if this is normal or not. After all, window units are designed to allow water to drip down.

    But if the water is flowing out somewhere it is not supposed to be, that is when you can suspect that a leak is present. An AC drain pipe dripping water on its end is normal, but dripping along its lines is not.

    Another indicator is when the water that seems to be coming out from your unit is more than the usual. A few drops of water every now and then is normal, but frequent dripping that cause puddles to form may not be.

    If you suspect that your unit is leaking on the outside, it usually is due to the following:

    • Drain pan that can no longer hold the amount of water flowing in because it is damaged, or there is too much water coming in
    • Blocked or damaged drain line
    • No drain line and/or drain pan present
    • Debris and dirt present on the outside of the unit, particularly on the coil, which causes increased condensation
    • Drain hole is clogged or damaged
    • Uneven installation

    Leaking outside the house from your window AC occurs less often than inside, and when it does, clogged components are the most likely cause.

    Window AC Spits Water

    Have you ever experienced getting close to your AC unit, such as when you switched it on, and suddenly experience an impromptu face wash via water coming out of its vents?

    It may sound far-fetched to you if you have yet to experience it, but it really happens, especially to window units. If it happens outside the house, it is normal. What is not normal is if the water is being spit out into the room via the vents.

    But how does this happen?

    The spitting water coming from an AC unit is due to the slinger ring that collects water present in the drain pan and splashes it to the coils for cooling purposes. These coils have the tendency to get hot and at risk of overheating, and splashing water over them prevents that problem.

    The slinger ring also helps make the air conditioner run more efficiently and lessens the amount of water present in the drain pan, minimizing the chance of an overflow and subsequent leak.

    This water should be expelled outside by the slinger ring, but if it happens inside, it is likely due to:

    • Clogged drain lines
    • Damage or blockage to the drain pan
    • Insufficient pitch on your unit
    • Frozen evaporator coils, particularly due to a dirty filter

    But, don’t worry. Resolving this issue because of any of the possible causes mentioned above is easy.

    How to Fix a Leaking Air Conditioner

    One thing you should know about leaks involving any air conditioning unit is that it generally involves the services of a professional. AC units are known to be sturdy, but it also consists of sensitive components that can get easily damaged.

    Most of the parts that are involved in leaks are those that should be carefully handled, such as the coils and other internal components. One wrong move in handling their repair would often mean very expensive repairs, or even irreparable damage.

    On the other hand, minor leaks that involve detachable components, like the drain pipes and lines, may be resolved through DIY work. But even if this is the case, you have no idea if there are also other underlying issues on your unit that caused the leak. You’re lucky if the leak stops only by you having to replace the drain lines or pan successfully.

    But before you get in touch with a qualified HVAC technician, you can do some minor troubleshooting first to see if this completely solves the leak:

    1. Start with changing your thermostat settings. Sometimes, this often-overlooked aspect is actually responsible for the AC units sweating or producing too much condensation. Using new settings may solve it.
    2. Clean your unit’s air filter. If you have a filter full of dirt, it causes water to freeze up on the coils of your unit that leaks when it starts thawing. By cleaning the filter, air flows much freely, lessening the formation of frost or ice.
    3. Check the condition of the drain hole and any connected components. Window units come with drain holes where drain lines and/or pans are usually attached. Clogging on the drain line can cause water to back up.

    If your window unit is easy to reach, you can poke the drain hole with a wire until the blockage gets dislodged, or until trapped water starts flowing out. Also, reconnect the drain line and/or pan if they have become loose but seem to be undamaged.

    But if the drain hole is free of any blockage and the leaking occurs outside, you may have to replace the drain pan and lines, or ensure that they have a tight connection. Leaking may be happening because they are in poor condition or have loosened up.

    But if any of these steps do not stop the leaking on your unit, or your window AC is installed on a higher floor, professional help is definitely needed. Not only is the fix going to be challenging, the danger involved will also increase. Any work that involves heights and climbing up a ladder, including working on a window ac unit, is a safety risk.

    More often than not, fixing this will involve removing the unit from where it is installed. This will allow the technician to get a closer look and see what is actually causing the leak.

    If you are curious about how HVAC technicians fix it, here are the measures they follow to solve it:

    • Determine if the slope of the unit is sufficient. Window units should slope downwards, with the front panel at a higher level than the rear. Some installers, especially unlicensed ones, fail to follow this rule. As simple as reinstalling the unit and adding a slight pitch to it will stop the water from going into the room.

    Also, technicians will often check the level of the unit first before removing the unit to see if the pitch present is adequate.

    • The refrigerant level will then be checked. If insufficient refrigerant is present, it may cause the freezing on the coils that is causing the leak. If so, adding refrigerant solves it.
    • If the evaporator coils are dirty, they have to be cleaned up. The filter is not the only component of your unit that can get dirty; the coils will also trap in dirt. Dirty coils will increase the chances of frost inside your unit that causes the leak.
    • Check clogged components. Any blockage present must be removed, because this prevents water from draining properly. Your technician can also poke the blockage with a wire, or use tools, such as a vacuum, to unclog them.
    • Damaged insulation of the coils needs to be replaced. The insulation allows water from the coils to travel to the drain, and any cracks or holes present allow water to leak through your unit.
    • Add sealant to the sides of the unit. If everything still looks good with the components of your unit, the leaking may be due to gaps present between your unit and the window it is installed in. Covering those gaps with sealant will stop the issue.
    • If the condenser pump is broken, a more practical option is to get a new unit. Condenser pumps are vital to the unit, and even if it can still be salvageable, there is no guarantee how long you can rely on your unit to work.

    Even if you think that a minor fix is only needed, the safest option is to hire a professional for this task, especially if you have an older unit. He or she may see any other underlying issues that need to get fixed, not just make an accurate assessment of the problem.

    You may think that you are saving money by not hiring one, but you may miss out on warning signs that your unit is about to break down because you have no idea what to watch out for, aside from any obvious physical damage.

    What to Do If Your Window AC Uses R22 Refrigerant

    If you use an older AC unit, particularly one of those manufactured before 2010, chances are that it uses the R22 Refrigerant, also known as the Freon 22 or R22 Freon. If so, you may need to start saving up for a new unit soon.

    This specific refrigerant will soon be phased out due to the Montreal Protocol, which prohibits the use of ozone layer-depleting substances worldwide, including the R22 refrigerant. In fact, it is notorious for being among the biggest contributors to the damage being done to the ozone layer.

    This phasing out started back in 2003, but its production only started being regulated in 2010. By now, only certified technicians are allowed to purchase this particular refrigerant. And by January 2020, the production of new R22 refrigerants will be completely obsolete.

    And if you have a unit that uses this particular type, you may only use recycled refrigerants by 2020. And when the supply runs out, you have no choice but to upgrade to a new unit.

    But on the upside, a typical modern unit runs more economically and is also more environment-friendly, making the upgrade worth every cent. You also won’t feel guilty, because you are no longer contributing to the destruction of the ozone layer every time you switch on your AC unit.

    Getting Quotes for Your AC Maintenance

    Keeping an AC unit in good condition to prolong its life requires proper maintenance. And for that, a professional has to get involved.

    Even if you want to do the maintenance of your HVAC unit yourself, you are limited to the cleaning of the air filters only. Which, you should be doing every month, by the way.

    Having your AC unit undergo maintenance every now and then is not as expensive as it sounds. And if you are still on the fence about it, how does saving as much as 5 to 15% in terms of your consumption, which means a deduction on your household bills, sound to you?

    And if you are wondering where you should begin your search for a qualified HVAC technician to do maintenance work on your unit, you can start by looking for a comfortable chair to sit on while you use our service. Yes, with our help, you don’t need to step outside your home to do that.

    Did you know that by filling out our form, you can receive quotes for the maintenance of your AC unit from as much as four qualified technicians? And because they are aware that they are not the only ones who will be doing so, you are sure to get competitive quotes.

    Does that already sound good to you? But, it doesn’t stop there.

    There are two other important things you need to know:

    1. Our service is free of charge, and
    2. You are also free to turn them down if the offers you got from technicians are not satisfactory.

    Free quotes from up to four HVAC technicians, with no obligation to choose any of them just to avail the service. It definitely does not get better than this!

    So, let’s make sure that your AC unit is trouble-free and will last you a long time. Fill out our form now to get your unit checked out asap!

    And, don’t forget to make it a habit to regularly maintain your unit.

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